import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

from collections import defaultdict
from operator import mul
from functools import reduce

N,K = map(int,read().split())

factor = [defaultdict(int) for _ in range(N+1)]

for p in range(2,N+1):
    if factor[p]:
        continue
    q = p
    while q <= N:
        for i in range(q,N+1,q):
            factor[i][p] += 1
        q *= p

fN = factor[N]
pN = fN.keys()

best = 0
answer = 0
for n in range(2,N):
    f = factor[n]
    common = sum(min(f[p], fN[p]) for p in pN)
    if common < K:
        continue
    div_cnt = reduce(mul, (x+1 for x in f.values()))
    if div_cnt > best:
        best = div_cnt
        answer = n

print(answer)